Best way to send multiple files as HTTP response

I have a phoenix application from which a user can download multiple(5-6) files of size 1MB. I couldn’t find anything related to sending multiple files. I have tried send_file/5 but it can only send single files at a time.

Should I make these downloads independent or send all the files in bulk? Downloading in bulk helps me reduce the number of HTTP requests.

I don’t think you can send multiple files over a HTTP request. One option would be to add them to a zip.

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So that’s not precisely true, I mean it’s precise historically speaking but you have slightly more options nowadays with modern browsers. I’m not saying it’s good or easy options but there are.

One option would be to download the files to the browser’s memory with say JavaScript fetch API . Once you have the file in memory you can then save the file to the filesystem with file system JavaScript API (example:

One could approach this by concatenating the files server side, with some boundary marker in between, then download the files to browser memory, split it by boundary marker into multiple Blobs, then for each Blob trigger saving to filesystem.

I think at this point browsers (at least Chrome) would actually warn user that “this web site is trying to download multiple files” within a top bar pop up but user can still allow it.

Overall, I do not think it’s worth it. Just do multiple HTTP calls from web site to the back-end, or use ZIP to package multiple files into one.

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Thanks @hubertlepicki and @sarat1669

I think it won’t hurt getting all the images one at a time. JS’ Fetch API requires me to exercise extra caution. and might lead to bizarre errors.

I will go with multiple HTTP calls

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